Safety computer systems modeling

In the case of the real systems, the dynamic approach to the rehability analyse requires an important increase in performance by reason of the process variables development, human operators and control actions. In the recent years, the increased computer performance enabled including of the dynamic behaviour of the safety and reliabihty models. Through last ten years, several methods for solved of the dynamic reliability problem were formulated (Marseguerra and Zio 1996 Siu 1994 Labeau 1996). 

ABSTRACT The draft document of the NATO allied ordnance publication (AOP) 52 gives guidance on software safety design and assessment of ammunition-related computing systems. The content of the draft is reviewed and compared with the lEC 61508 standard for functional safety of electrical/electronic/programmable electronic (E/E/PE) systems. We discuss the overall development model, the safety-lifecycle model and proposed techniques and measures. We also investigate whether the functional safety concept of lEC 61508 is incorporated in the document. 

Bell R(2010) Introduction and revision of lEC 61508. SIAS 2010, Tampere, Finland Bishop P, Bloomfield R (1998) A methodology for safety case development. In Redmill F, Anderson T (eds) Industrial perspectives of safety-critical systems. Springer Docker TWO (1979) Some aspects of computer simulation modelling. In Computer performance evaluation - a professional development seminar. New Zealand Computer Society, Hamilton... 

In addition, just as employee participation is the key element of process safety management systems, worker involvement is crucial to the effective application of Safety Cases. Unfortunately, the perception among many that a Safety Case is a lengthy, highly technical document that can only be understood by specialists, mitigates effective employee participation. For example the Computational Fluid Dynamics (CFD) technique used to model explosion over-pressure uses very sophisticated mathematics. This sophistication makes communication with nonspecialists a challenge. In addition the sheer size and complexity of a Safety Case may serve as a barrier to the involvement of nontechnical personnel. 

The applicative case-study that supports the evaluation of the methodology and its associated tools is a system function called Compute traction orders . While being limited to one single system function, this case-study is representative of the system since it contains both critical and non-critical sub-functions and considers both realtime and operational constraints. The use-case will allow to structure and strengthen the development platform and framework of such systems, especially in the scope of multi-viewpoint system modelling (e.g. operational, functional, constructional, dysfunctional...). A simplified view of interoperability needs between system model, safety analysis and requirement management is represented in the following workflow ... 

Safety assessment requires the analyst to define criteria that distinguish normal operation from failure of a system. The analysis method proposed by this paper requires implementing these criteria in a system model, such that an output signal indicating the system status is computed. A system model is simulated by the analysis method for various combinations of intact and failed components, and... 

Systemic risk can thus be defined as the potential for systemic failure. Systemic approaches have been, or are being, implemented to control complexity, particularly through the creation of global installation models designed to smdy important properties such as safety or availability. These quantitative RAMS (Reliabilty, Availability, Maintainability and Safety) models, based on probabilistic approaches, are fairly well accepted for their representation of pure hardware elements (random failures) and human factors. They are much less so for their representation of deterministic aspects of computer systems (systemic or systematic failures). 

Gabbar, H.A. (200Ij) Object-Oriented Modeling of Computer-Aided Plant Enterprise Safety Management System (CAPE-SAFE), 11 International Conference on Computer Theory and Applications ICCTA 2001, Alexandria, Egypt, August-2001. 

The elucidation of actinide chemistry in solution is important for understanding actinide separation and for predicting actinide transport in the environment, particularly with respect to the safety of nuclear waste disposal.72,73 The uranyl CO + ion, for example, has received considerable interest because of its importance for environmental issues and its role as a computational benchmark system for higher actinides. Direct structural information on the coordination of uranyl in aqueous solution has been obtained mainly by extended X-ray absorption fine structure (EXAFS) measurements,74-76 whereas X-ray scattering studies of uranium and actinide solutions are more rare.77 Various ab initio studies of uranyl and related molecules, with a polarizable continuum model to mimic the solvent environment and/or a number of explicit water molecules, have been performed.78-82 We have performed a structural investigation of the carbonate system of dioxouranyl (VI) and (V), [U02(C03)3]4- and [U02(C03)3]5- in water.83 This study showed that only minor geometrical rearrangements occur upon the one-electron reduction of [U02(C03)3]4- to [U02(C03)3]5-, which supports the reversibility of this reduction. 

Preclinical cardiac safety assessment of pharmaceutical compounds using an integrated systems-based computer model of the heart. Progress in Biophysics and Molecular Biology, 90, 414-443. 

Bottino, D., Penland, R.C., Stamps, A., Traebert, M., Dumotier, B., Georgiva, A., Helmlinger, G. and Lett, G.S. (2006) Preclinical cardiac safety assessment of pharmaceutical compounds using an integrated systems-based computer model of the heart. Progress in Biophysics and Molecular Biology, 90, 414-443. 

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